Resuming rendering image sequence after blender crash
Blender actually can do this already; if you disable Overwrite in Render settings > Output, Blender will skip rendering frames where the output file already exists.

See Does Blender resume rendering after returning from hibernation in Windows 7?



On linux you could write a short shell script to restart the render in case of a crash, e.g.

#!/usr/bin/env bash
while true; do
    blender $@ # $@ contains all the arguments passed to the shell script
done


Save it in a file (e.g. persistent_blender.sh), give it execute permissions and run it like so:

./persistent_blender.sh -b '/path/to/file.blend' -a


Where the arguments tell blender to render the animation of the specified file.

Of course you could make something much nicer and handle all sorts of things (such as stopping when all the output files exist and have a size > 0).